nAChRs gene expression and neuroinflammation in APPswe/PS1dE9 transgenic mouse.

An evaluation of the APPswe/PS1dE9 transgenic AD mouse, presenting with the toxic Aß1-42 deposition found in human AD, allowed us to characterize time-dependent changes in inflammatory and cholinergic markers present in AD. Astrogliosis was observed in cortex and hippocampus, with cellular loss occurring in the same areas in which Aß plaques were present. In this setting, we found early significantly elevated levels of IL-1ß and TNFα gene expression; with the hippocampus showing the highest IL-1ß expression. To investigate the cholinergic anti-inflammatory pathway, the expression of nicotinic receptors (nAChRs) and cholinesterase enzymes also was evaluated. The anti-inflammatory nAChRα7, α4, and ß2 were particularly increased at 6 months of age in the hippocampus, potentially as a strategy to counteract Aß deposition and the ensuing inflammatory state. A time-dependent subunit switch to the α3ß4 type occurred. Whether α3, ß4 subunits have a pro-inflammatory or an inhibitory effect on ACh stimulation remains speculative. Aß1-42 deposition, neuronal loss and increased astrocytes were detected, and a time-dependent change in components of the cholinergic anti-inflammatory pathway were observed. A greater understanding of time-dependent Aß/nAChRs interactions may aid in defining new therapeutic strategies and novel molecular targets.

Unraveling the adult cell progeny of early postnatal progenitor cells.

NG2-glia, also referred to as oligodendrocyte precursor cells or polydendrocytes, represent a large pool of proliferative neural cells in the adult brain that lie outside of the two major adult neurogenic niches. Although their roles are not fully understood, we previously reported significant clonal expansion of adult NG2-cells from embryonic pallial progenitors using the StarTrack lineage-tracing tool. To define the contribution of early postnatal progenitors to the specific NG2-glia lineage, we used NG2-StarTrack. A temporal clonal analysis of single postnatal progenitor cells revealed the production of different glial cell types in distinct areas of the dorsal cortex but not neurons. Moreover, the dispersion and size of the different NG2 derived clonal cell clusters increased with age. Indeed, clonally-related NG2-glia were located throughout the corpus callosum and the deeper layers of the cortex. In summary, our data reveal that postnatally derived NG2-glia are proliferative cells that give rise to NG2-cells and astrocytes but not neurons. These progenitors undergo clonal cell expansion and dispersion throughout the adult dorsal cortex in a manner that was related to aging and cell identity, adding new information about the ontogeny of these cells. Thus, identification of clonally-related cells from specific progenitors is important to reveal the NG2-glia heterogeneity.

Expression Profiling of Cytokine, Cholinergic Markers, and Amyloid-ß Deposition in the APPSWE/PS1dE9 Mouse Model of Alzheimer's Disease Pathology.

BACKGROUND: Alzheimer's disease (AD), a neurodegenerative disease, is associated with dysfunction of the olfactory and the entorhinal cortex of the brain that control memory and cognitive functions and other daily activities. Pro-inflammatory cytokines, amyloid-ß (Aß), and the cholinergic system play vital roles in the pathophysiology of AD. However, the role of changes in cholinergic system components, Aß accumulation, and cytokines in both the olfactory and entorhinal cortex is not known clearly. OBJECTIVE: The present study is aimed to evaluate the changes of cholinergic system components, Aß accumulation, and cytokines in both the olfactory bulb (OB) and entorhinal cortex (EC) of young and aged APPSWE/PS1dE9 transgenic (Tg) mice. METHODS: We have explored the changes of cholinergic system components, Aß accumulation, and expression profiling of cytokines in the OB and EC of aged APPswe transgenic mice and age-matched wild type mice using quantitative Real-Time PCR assays and immunohistochemistry techniques. RESULTS: In aged Tg mice, a significant increase of expression of interleukin (IL)-1ß, tumor necrosis factor (TNF)-α, and chemokine MCP1 (p < 0.001, p < 0.001, and p = 0.001, respectively) and a significant reduction of nAChRα4 (p = 0.048) and AChE (p = 0.023) was observed when compared with age-matched wild type mice. Higher levels of AChE and BuChE are expressed in OB and EC of the APPSWE/PS1dE9 of Tg mice. Aß accumulation was observed in OB and EC of the APPSWE/PS1dE9 of Tg mice. CONCLUSION: The study demonstrates the expression profiling of pro-inflammatory cytokines and cholinergic markers as well as Aß accumulation in OB and EC of the APPSWE/PS1dE9 Tg mice. Moreover, the study also demonstrated that the APPSWE/PS1dE9 Tg mice can be useful as a mouse model to understand the role of pro-inflammatory cytokines and cholinergic markers in pathophysiology of AD.

A novel KCNQ4 pore-region mutation (p.G296S) causes deafness by impairing cell-surface channel expression.

Mutations in the potassium channel gene KCNQ4 underlie DFNA2, a subtype of autosomal dominant progressive, high-frequency hearing loss. Based on a phenotype-guided mutational screening we have identified a novel mutation c.886G>A, leading to the p.G296S substitution in the pore region of KCNQ4 channel. The possible impact of this mutation on total KCNQ4 protein expression, relative surface expression and channel function was investigated. When the G296S mutant was expressed in Xenopus oocytes, electrophysiological recordings did not show voltage-activated K(+) currents. The p.G296S mutation impaired KCNQ4 channel activity in two manners. It greatly reduced surface expression and, secondarily, abolished channel function. The deficient expression at the cell surface membrane was further confirmed in non-permeabilized NIH-3T3 cells transfected with the mutant KCNQ4 tagged with the hemagglutinin epitope in the extracellular S1-S2 linker. Co-expression of mutant and wild type KCNQ4 in oocytes was performed to mimic the heterozygous condition of the p.G296S mutation in the patients. The results showed that the G296S mutant exerts a strong dominant-negative effect on potassium currents by reducing the wild type KCNQ4 channel expression at the cell surface. This is the first study to identify a trafficking-dependent dominant mechanism for the loss of KCNQ4 channel function in DFNA2.